Heat exchange media



Patented Apr. 12, 1949 HEAT EXCHANGE MEDIA John C. Zimmer, Union, N. J.,assignor to Standard 011 Development Company, a corporation of DelawareNo Drawing. Application December 30, 1944, Serial No. 570,775

13 Claims. 1

This invention relates to aqueous compositions adapted for use incirculating systems to effect heat or pressure transfer under conditionswhere one or more of the components may be partially volatized orsubject to ebullition. and particularly to such type compositions whichare substantially non-foaming. The present application is acontinuation-in-part of application Serial No. 513,477, filed December8, 1943, now abandoned.

It was disclosed in application Serial No.

' 513,477 that the addition of certain insoluble or substantiallyinsoluble metallo-organic compounds to spumiferous liquid compositionscontaining water or alcohols, glycols, glycerols, etc., reduces thetendency of such compositions to form foam when subjected to reducedpressure or heat treatment. The particular metallo-organic compoundsdisclosed were the alkyl, aryl, cyclic, oxyalkyl, 'oxyaryl; halogenatedalkyl, aryl, oxyalkyl and oxyaryl derivatives of such metals as silicon,titanium, germanium and zirconium and polymers thereof having from 2 to50 metalloid or metal atoms in the molecule.

The desired compounds disclosed were stated as having an empiricalformula:

R1 12,- no- OM-OH wherein R1 and R2 represent hydrocarbon, halogenatedhydrocarbon, oxyhydrocarbon radicals; or hydrocarbon radicals containingnitrogen, phosphorus, sulfur and related elements: M represents anelement such as silicon, titanium,

germanium or zirconium and n is a number from 1 1 to 25 inclusive. The0H radicals in the formula may remain as such or be substituted ascommonly occurs in characteristic reactions.

Where R1 and R2 in the foregoing general formula are aromatichydrocarbon groupings, intrasubstituents may also occur. Suchintra-substituents may be a halogen; a nitrogen-containing radical suchas N03, NH2, etc., a sulfur-containing radical such as SH or 803K, or aphosphorus-containing radical such as phosphate, phosphite,thiophosphate or thiophosphite. These substituents may be present assubstituent radicals on the aromatic nucleus before or after a polymerformation. Similarly, in the general I formula, in which R1 and R2 arealiphatic hydrocarbon radicals, intra-substituents of the radical mayoccur before and after the formation of a complex polymer.

In the case of the silicon compounds, they are generally known as"silicone oils. These silicon compounds can be made by a variety ofmethods, and very conveniently by reacting a Grignard reagent with ahalide of the metal and hydrolyzing the resulting reaction product, andthen condensing with the elimination of water. Other methods are known,some of which are described in U. S. Patents 2,258,218; 2,258,219;2,258,220; 2,258,221; and 2,258,222. Derivatives characteristic of thehydroxyl functional group may also be prepared byreaction of theterminal hydroxyl groups of one or more of the silicone molecules. Inaddition to the silicones" other organic compounds of silicon such asthe silicanes and insoluble or partially insoluble silicate esters, aswell as the corresponding organic compounds of titanium, germanium, andzirconium, may be used for the processes of the present invention.

Representative examples of the metallo-organic compounds disclosed inapplication Serial No. 513,477 are dimethyl silicone, methyl phenylsilicone, ethyl butyl silicone, chloro butyl silicone, germanium phenylpolymers; methyl cyclohexyl silicone, dicyclohexyl silicone, diphenylsilicone, hydroxy phenyl methyl silicone, phenyl ethyl silicone, phenylpropyl silicone, phenyl isopropyl silicone, tolyl butyl silicone, tolylamyl silicone, xylyl isopropyl silicone, xylyl methyl silicone, phenylhydroxy ethyl silicone, xylyl hydroxy propyl silicone, tolyl hydroxypropyl silicone, hydroxy phenyl hexyl silicone, phenyl stearyl silicone,and phenyl oleyl silicone, trichlorphenyl silicone, fluoro phenylsilicone, chloronaphthyl silicones, polyalkyl, polyaryl titaniumderivatives. The metallo-organic compounds disclosed in my parentapplication are, in general, inert, colorless, odorless and oily liquidspossessing an unusually low rate of change of viscosity withtemperature. The compounds remain permanent liquids over a wide range oftemperatures, they are resistant to oxidation, and they arecharacterized by very low surface tensions. A representative compound ofthe class has a freezing point of 40" C., specific gravity at 30 C. of0.9634; refractive index at 30 C. of 1.4013, and a surface tension of22.7 dynes per square centimeter. The compounds are substantiallynonvolatile at ordinary temperatures but show appreciable vapor pressureat temperatures above their pound pounds are that they are completelysoluble in liquids. They are, however, substantially insoluble in water,alcohols. esters,,glycols, alkyl or cyclic hydrocarbons and particularlypetroleum lubricating oil. fats. soaps, etc., and thus may be employedas foam suppressors in these media or mixtures of these media.

It was disclosed in our parent application that the metallo-organiccompounds could be placed in the reactor by any convenient method oradded to the spumiferous composition undergoing treatment normallyproductive of foam development either before or after the compositionhas been charged to the processing equipment. in an amount in the caseof dehydration equivalent to from 1 to 100 grams per thousand squareinches of evaporating surface. Since many evaporation vessels have orprovide irregular evaporating surfaces. the amount of metallo-organiccompound added in a dehydration process to the spumiferous compositioncan be calculated on the basis of weight per cent of the charge to theevaporator. Expressed in this manner, it usually only requires from/1.ooo,ooo to several per cent by weight, (based on the total charge).preferably from 0.000001-1%, to suppress frothing or the formation ofpersistent foams during subsequent evaporation, and the dehydration canbe conducted rapidly without danger of overflowing the vessel or theoccurrence of throwover through a condenser. The processes can be runeither by a batch method or continuously.

It is believed that the metallo-organic compounds either are dispersedas minute particles throughout the body of the liquid which usually isnot evident as a haze or cloud, under ordinary examination although thediscrete particles of the froth-suppressing compound may be evidentunder dark field microscopic examination or that they form an extremelythin layer on the surface of the material being evaporated whichoperates to break up the bubbles of steam or water vapor as the bubblesreach the surface layer. It is also believed that those metalloorganiccompounds, even though they may be heavier than either 011 or water, canconcentrate on the upper surface of the liquid because of their surfacetension characteristics. Further, it appears that they also tend todisperse themselves throughout the liquid as minute droplets which actto destroy froth bubbles throughout the body of the liquid.

One possible explanation for the foam-breaking phenomenon of themetallo-organic compounds is that when a bubble comes in contact with alayer or particle of the insoluble metalloorganic compound, the liquidforming the bubble envelope is repelled by the metallo-organic comor isdisplaced because of surface tension effects. thus forming a thin spotin the bubble envelope which then ruptures at this point. allowing thevapor to escape. No limitation, however, is considered with regard tothe invention as a result of any such theory as to the foam sup namely,the cooling of the engine. Moreover, one of the causes of this foamingseems to be the vaporization of some of the low boiling constituents ofthe anti-freeze compositions in the areas of localized high temperatureof the surface to be cooled. forming vapor bubbles. Whatever may be thecause, however. it has been found that the metallo-organic compoundsdisclosed in application'serial No. 513,477 are effective in repressingthe foaming tendencies of antifreeze compositions consisting largely ofaqueous alcoholic solutions.

In commercial anti-freeze solutions, the lower boiling water solublealiphatic alcohols, and polyhydrlc alcohols, the glycols and glycerols,are the freezing point depressant materials admixed with water. Thesealcohols loosen and detach from the walls of the confining vessels suchmaterials as iron rust which with water alone remain attached. Thismaterial, especially in forced circulation systems, collects in thepipes and finally clogs the system. Furthermore, an alcohol solution hasa lowersurface tension than that of water and as. a result the solutionspass through any soldered portions and minute crevices through whichwater alone does not usually seep. It is therefore desirable to preventcorrosion of the metal and also, if possible, to coat the equipment witha water-insoluble, water-repellant material which will prevent theaqueous solution from penetrating into cracks and crevices and escapingor leaking out of the system.

It is an object. therefore. of this invention to prepare aqueous oralcoholic heat exchange media. especially for internal combustion engineradiators, jacketed kettles, autoclaves, heat exchange tubes andrefrigerator coils which have a highly desirable temperature range ofliquid condition involving high heat capacities and low viscositycharacteristics coupled with chemical inertness and physical propertieswhich render the compositions substantially non-corrosive to themetallic and non-metallic parts of the confining equipment and also aresubstantially nonfoaming under partially or totally vaporizingconditions, and show little tendency to creep under service conditions.Other objects of the invention will be apparent from reading thefollowing description.

The composition of the invention has, in addition to theusualconstituents of heat exchange media suitable for use at lowtemperatures. one

or more of the metallo-organic compounds disclosed in the parentapplication Serial No. 513,477. It has been found that small quantitiesof these metallo-organic compounds in the compositions are particularlyeffective in reducing pressing action of these metallo-organiccomfoaming of the desired aqueous or alcohol-containing fluids. Theeffects appear to be common to all the metallo-organic compounds andanalogous metalloid-containing organic compounds, more particularly tothe silicone oils in which the integer in the general formula of thesilicon compoundsis from 5 to 20. p

The non-foaming compositions within the scope of the invention comprisea water-soluble alcohol having up to 5 carbon atoms in the molecule,such as ethanol or other monohydric alcohol. a glycol, especially a1,2-glycol, glycerol or a mixture thereof, water, and one or more of themetallo-organic' compounds disclosed in the parent application. Usually,however, in addition to these ingredients there are present a corrosioninhibitor such as an organic amine or an organic nitrite, suitablealkaiizing, and buffer compounds, and a sealing agent such as paper pulpor linseed meal; according to the service for which the composition isadapted.

In preparing compositions according to the invention, a concentratedcomposition'is first prepared and then, by diluting the concentrate withwater in various amounts, the hydraulic media of various freezing pointsare prepared. The composition of a basic concentrate may be ex- To whichis added:

Light lubricating oil 76 cc./gal. of alcohol concentrate (32 secondsSaybolt vis. at 100 F.) Natural Alphazurine 2G-dye g./gallon..- 0.04Sodium nitrite do 4 Sodium carbonate do 1 Disodium phosphate do 4Linseed meal do 5" The metallo-organic compounds are incorporated insuch concentrates in an amount between =2 0.000001% and 1.0%. Theresultant blended compositions are then diluted with various quantitiesof water. Thus, 15% aqueous composition, Example I, had a freezing pointof 20 F.;

27.5% solution, a freezing point of 10 F.; and

35% solution, a freezing point of 0 F. Eor Ex; ample II for protectionto a temperature of 20 F.,

a 15% aqueous solution is prepared, and for temperatures of about 0 F.,a 30% aqueous solution is prepared.

In the preparation of concentrated composition of Example I, the mixtureof ethylene and propylene glycols may vary in the-ranges from 90% to 10%ethylene glycol and from 10%"to'90% propylene glycol. Instead of amixture of these glycols, a mixture of any of the several 1-2 glycolscontaining up to about 5 carbon atoms may also be employed. Glycerol mayalso be used. The advantages of employing the glycols and glycerol arethat in addition to their water solubilities and low freezing and highboiling points, the compositions at low temperatures'form slurries orhighly viscous masses previous to solidification and the pressureexerted upon complete solidification is insufficient to cause crackingor breaking of the metallic walls of the confinin equipment. The glycolsare preferable to glycerol in the preparation of anti-freeze solutionsfor automobiles because glycerol in contact with piston valves and otherengine parts into which the solution may come into contact in servicedue to leakage through gaskets produces a sticky or resinous materialnecessitating in many cases costly repairs. The amounts in which theglycols and glycerol present time often used. These alcohols aregenerally employed as mixtures such as methyl and isopropyl alcohols asshown in Example II, and

sometimes as a mixture of ethyl and isopropyl alcohols. In theconcentrates of the type of Example II, the mixtures of methyl andisopropyl alcohols may vary from 90% to 10% methyl alcohol, and from 10%to 90% of isopropyl alcohols in order to prepare mixtures of specificgravity of about 0.81.

The amount of water in the concentrated compositions is roughly thatgiven in the specific example, although varying quantities of water maybe employed in the heat exchange equipment or radiator, depending uponfreezing or boiling point desired.

Instead of sodium nitrite as corrosion inhibitor, other inorganicnitrites may be used, especially potassium and calcium nitrites. Organicamines, metal soaps and petroleum sulfonates are advantageous corrosioninhibitors in many cases. In an automobile radiator many metals occur incontact with each other. Electrolytic effects play a considerable partin the corrosion of automobile radiators. For this reason it has beenfound advisable in many cases to employ a mixture of corrosioninhibitors rather than any one individually. Organic amines which havebeen found especially advantageous are cyclohexylamine anddicycl'ohexylamine. The amounts in which the various corrosioninhibitors are used depend greatly on service to which the heat exchangemedia are to be adapted, but in general the amounts are about that givenfor sodium nitrite in the specific example.

The sodium carbonate and disodium phosphate given in the specificconcentrated compositions are examples of a buffer combination for a pHrange of between 10 and 11.5. Other buffer combinations functioning overthis pH range which are soluble in the final compositions and which donot react with the other constituents to form electrolytes havingundesirable corrosive tendencies may be employed.

A disadvantage of usin alcohol compounds in the preparation ofanti-freeze solutions is their characteristic of imparting to thecomposition a lower surface tension than water and thus causingincreased creepage effects. This activity is usually counteracted in thecompositions of the invention by'the addition to the mixture ofcompounds of the type of linseed meal which tend to seal or plugcrevices, thus preventing leakage. Other compounds which may be used toreduce this form of leakage are gum gambler, tragacanth, quince seed,Irish moss and their mixtures. Other well dispersed solids may beincluded such as paper pulp, aluminum bronze, etc. The metalloorganiccompounds herein disclosed are not only insoluble in water but alsorepel water, and are also insoluble in aqueous alcoholic solutions.Further, in view of their low surface tension, they spread in very thinfilms on the surface of water solutions and tend to be absorbed onmetals. Thus, as pointed out in the parent case, the metallo-organiccompounds form thin coatings on metallic surfaces. This feature isparticularly advantageous in regard to cracks and crevices in metallicsurfaces since, because of their ability.

not to be wetted by aqueous solutions and to repel aqueous solutions,the presence of the especially in the cracks, prevents leakage of theconstituents from the radiator or other containis between 6 and 20, andR1 is an aliphatic hydrocarbon radical and R2 is an aromatic radical.

The compositions of this invention were investigated for foamingcharacteristics by heating and shaking solutions so as to produce anappreciable amount of foam. In this manner it was found that aqueoussolutions of mixtures of (1) methyl and isopropyl alcohols, (2) ethyleneand proylene glycols, and (3) glycerine, showed a negligible foamformation in the presence of silicone compounds. As a specificillustration of a composition employed as an anti-freeze solution, thefollowing compositions were prepared:

The following data were obtained:

Time for Foam to Break Blend A Over 5 minutes Blend B 1 minut Thiscomparison of data indicates that the sillcone oil compounds reduce theamount of foam produced and that the foam produced in the presence ofthese compounds breaks more easily, and is of a finer texture and lessobstructive in character than that produced in the absence of thesilicone compounds.

The heat exchange media prepared by diluting the concentratedcompositions are liquidover a wide temperature range and when cooled totemperatures at which solidification commences highly viscous orsemi-solid masses are obtained rather than immediately solid masses. Inthe various stages of dilution the compositions are non-corrosive andlittle or no material is deposited on to the surfaces of the confiningvessels. Thus, with the negligible corrosion and the maintenance ofclean heat transfer surfaces, the efliciency of the cooling system ismaintained at a high standard by use of the compositions of the presentinvention.

It will be apparent to those skilled in th art that numerousmodifications can be made in the compositions previously disclosed.These modifications are not excluded from within the scope of thepresent invention. It it intended to include all such modificationswithin the scope of the present invention and to be limited only by theappended claims.

What is claimed is:

1. An aqueous composition suitable for use in heat exchange and pressuretransmitting systems consisting essentially of a mixture of a lowerboiling water-soluble aliphatic alcohol and water as the mainconstituents and in minor proportions a water in soluble liquid compoundhaving the general formula Lix n1.

wherein R is a hydrocarbon radical selected from the group consisting ofaliphatic, cycle-aliphatic and aromatic hydrocarbon radicals, R is ahydrocarbon radical selected from the group consisting of aliphatic,cycle-aliphatic and aromatic hydrocarbon radicals; X is selected fromthe groupconsisting of hydrogen, chlorine, bromine, iodine and fluorine;M is anelement selected from the group consisting of silicon, titanium,germanium, and zirconium and n is an integer from 1 to 25.

2. A liquid composition suitable for use in heat exchange and pressuretransmitting systems consisting essentially of a mixture of awatersoluble aliphatic alcohol and water as the main constituents and inminor proportions a waterinsoluble liquid compound having the generalformula Li ii.

wherein'R is a hydrocarbon radical, M is an element selected fromthegroup consisting of silicon, titanium, germanium and zirconium, and nis an integer from 1 to 25.

3. Aliquid composition according to claim 2 in which the water-solublealcohol is a polyhydric alcohol having up to five carbon atoms in themolecule. 7

4. A liquid composition according to claim 2 in which the water-solublealcohol is a monohydric alcohol having up to five carbon atoms in themolecule.

5. A liquid composition according to claim 2 in which the water-solublealcohol is a dihydric alcohol having up to five carbon atoms in themolecule.

6. A liquid composition according to claim 2 in which the water-solublealcohol is a trihydric alcohol having up to flve carbon atoms in themolecule.

7 A liquid composition suitable for use in heat exchange and pressuretransmitting systems consisting essentially of a mixture of a 1-2 glycolhaving up to about-five carbon atoms in the molecule and water as themain constituents and from .000001 to 1.0% by weight of awater-insoluble liquid compound having the general formula 11 n no si-o-s i o n Li, ii.

HO- i i 0H Li. 1.1.

wherein R1 is an aliphatic hydrocarbon radical, R: is an aromatichydrocarbon radical, and n is an integer from 6 to 20.

9. A liquid composition according to claim 8 in which the 1-2 glycol isa mixture of ethylene and 1-2 propylene glycols.

10. A liquid composition according to claim 8 in which the buffer-salt.is a mixture of sodium carbonate and disodium phosphate.

11. An anti-freeze solution suitable for use at low atmospheric wintertemperatures in automobile engine cooling systems consisting essentiallyof a mixture of specific gravity of about 1.0775 of ethylene andpropylene glycols and water as main constituents, to which are added acorrosion inhibitor of the class consisting of sodium nitrite andcyclohexylamine, sodium carbonate and disodium phosphate in amounts toexert bufler action for the pH range of from 10 to 11.5 and 0.000001% to1.0% of a water-insoluble liquid compound of general formula Ho ie-31011 L L: lax-I- wherein R1 an aliphatic hydrocarbon radical. R: is anaromatic hydrocarbon radical, and 1: is an integer from 6 to 20. v

12. A liquid composition suitable for use in heat exchange and pressuretransmitting systems 10 which consists essentially of an alkalinesolution of pH from 10 to 11.5 of a water soluble polyhydric aliphaticalcohol, water and a silicone compound dontaining hydroxyl groups bondedto its terminal silicon constituents.

13. An anti-freeze solution suitable for use at low atmospheric wintertemperatures in automobile cooling systems which consists essentially ofa mixture of a water soluble polyhydric aliphatic alcohol and water asmain constituents and in minor proportions a corrosion inhibitor and asilicone oil compound containing hydroxyl groups bonded to its terminalsilicon constituents.

JOHN C. ZIMMER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,213,368 Hibbert Jan. 23, 19171,988,584 Dana et al Jan. 22, 1935 2,071,482 Winning et al. Feb. 23,1937 2,233,185 Smith Feb. 25, 1941 2,258,222 Rochow Oct. 7, 19412,375,007 Larsen May 1, 1943 2,349,338 Capsadle May 23, 1944 2,384,384McGregor et al. Sept. 4, 1945 OTHER REFERENCES

